Atoms and molecules in the air move constantly. 【小题1】 In high-pressure systems, the molecules inside the system move faster than those that surround it. The opposite occurs in low-pressure systems, where the air inside the low is moving more slowly than in the surrounding area.

Air flows around a high-or low-pressure system in much the same way as water swirls (旋涡) around a hole. In the Northern Hemisphere, air that moves into a high-pressure system flows outward in a clockwise pattern. Air flowing upward in a region of low pressure moves counterclockwise. 【小题2】

Air is more dense (密集的) in a region of high pressure, so the air pushes out toward less dense regions. The air mass begins to warm as it goes down, which prevents the formation of clouds. The presence of clouds indicates that rain may be present in the air. 【小题3】 In a region of low pressure, the air rises. As it does, the air mass cools and clouds form from the humidity (湿气) inside the air mass.

【小题4】Once the droplets are heavy enough, they fall to the ground. When temperatures are warm, rain is the result. If temperatures are low? the result is snow. When water droplets fall through relatively warmer or colder air masses on the journey to Earth, the low- pressure system may bring snow or ice.

Rain associated with low-pressure systems holds true in much of the Northern Hemisphere. 【小题5】 So in tropical areas, rain association with highs or lows is less predictable.

In some areas of California, it’s so dry that farmers aren’t willing to plant crops this season. Growers, north of San Francisco, have begun pulling out of local farmers markets.

County Line Harvest, which farms more than 30 acres in Petaluma, hasn’t had enough water to grow all the peppers, lettuces and other produce for a long time, according to a video on its Instagram page. Nearby farms are saying the same, emphasizing (强调) the effect of the extended dry periods.

California grows a third of the United States' vegetables and two-thirds of the nation's fruits and nuts. If dry weather prevents farmers from growing plants, that could lead to pushing up the price of food that's already starting to affect the U.S. economy.

“Due to severe drought, for the first time in 21 years, we will not be able to grow this summer in Petaluma ," County Line said in its post.

Drew Lerner, president of World Weather Inc. in Kansas, said California “missed the rainy season" and won't see much moisture (水分) over the next several months.

A La Nina weather pattern in the Pacific pushed winter storms north and away from the state, leaving it with less moisture than usual. As California gets most of its water from winter storms, little relief is expected before October.

That has left growers such as Shao Shan Fann in a bind. The business can’t offer the selection of Asian vegetables and Bay Area staples it usually grows at its Bolinas location, according to its website.

Nearby, Green Valley Community Farm has access to only about 5% of the water it usually relies on, owner David Plescia said. He’s looking for new land with enough water to use, and also has a permit in the works to grow cannabis to make up for the lost income. If it doesn’t make it, he’ll leave the fields empty.

“It’s part of our generation’s cross to bear, figuring out how to run small — or medium-scale farm businesses in this kind of atmosphere of highly variable rainfall,” Andrew said.

Six years ago, as the Paris Accord was agreed at the 21st UN climate conference, the French hosts wisely insisted on an item urging countries to match promises with deeds.

Having committed to try to hold global temperature rises “well below” 2℃ compared to preindustrial times, governments were commanded to produce updated plans in 2020, showing how they would actually achieve that goal.

This year’s extreme weather events—the terrible heatwaves, wildfires and floods that have made headlines across the globe—are evidence that the destructive consequences of global heating are happening faster than expected and on a larger scale. The world today is 1.1-1.2℃ hotter than in the preindustrial era. Heating beyond 1.5℃ would deliver even more devastating droughts and crop failures. It would increase the chances of greater famine and ecosystem collapse.

The European Union has suggested new law on industrial emissions, transport and carbon-intensive imports, designed to cut emissions to 55% below 1990 levels by 2030. These moves reflect a delayed sense of urgency; but time is running out in the race to close the gap between the total emissions cuts proposed by countries and the level actually required.

Cop26 is unlikely to produce the drama of a Paris-style breakthrough; but it must pave the way for concerted global action to speed up emissions cuts. Concrete measures are required in areas such as consuming less coal, reducing methane gas emissions preserving forests and lands, and financing climate improvement in developing nations.

What is done and left undone this decade will determine the fate of future generations. As a UN pre-summit spokesman put it last week, “Eight years to make the plans, put in place the policies, carry out them and ultimately deliver the cuts. The clock is ticking loudly.”